1. Field of the Invention
The present invention relates to a substrate transport apparatus which transports flat substrates, and an adjustment method of a substrate transport path in said apparatus.
2. Description of the Prior Art
An example of this type of substrate transport apparatus of the prior art is that provided in a wire bonder, an example of which is shown in FIGS. 1 through 3. Furthermore, since said apparatus is disclosed in, for example, Utility Model Laid-Open Publication No. 3-48225, the following explanation is limited to its essential portion only.
In said wire bonder, substrates in the form of a plurality of lead frames L/F, on which are respectively mounted a plurality of IC chips (semiconductors) 1 in a row in the lengthwise direction, are arranged and contained in a substrate containment device in the form of magazine M, and this magazine M is loaded onto loader 2. These lead frames L/F are sequentially removed from magazine M by a frame feeding device not shown accompanying operation of said loader 2, intermittently fed at intervals of the arrangement pitch of IC chips 1, and transported onto heater plate 5 which is heated by heater block 4 (see FIG. 3). On said heater plate 5, each IC chip 1 mounted on said lead frame L/F and lead 8 formed on said lead frame (see FIG. 2) are sequentially connected by bonding using a conductive wire by bonding device 7.
Those lead frames L/F on which the above-mentioned bonding has been performed are further fed backward by the above-mentioned frame feeding device and contained in empty magazine M loaded on unloader 9.
A transport path that performs high-precision transport to prevent snaking of lead frames L/F transported by the above-mentioned frame feeding device is set, and said transport path is demarcated by guide members in the form of a pair of guide rails 11 and 12 arranged corresponding to both sides of lead frames L/F.
Furthermore, following completion of wire bonding, an indentation is formed in lead frame L/F as shown in FIG. 3 for the purpose of reducing the thickness of finished products in the form of semiconductor components obtained by plastic molding and so forth, and IC chips 1 are mounted using said indentation in the form of island 13. The above-mentioned transport path is particularly important for positioning said island 13 with respect to indentation 5a provided in heater plate 5 so that said island 13 is aligned during bonding work.
However, since lead frames L/F have various widths corresponding to the type of IC chip 1 which is to be mounted, the interval between both guide rails 11 and 12 is adjustable to allow guiding of these various types of lead frames. More specifically, as shown in FIG. 2, a pair of frame bases 15 are fixed on the frame of the wire bonder (not shown), and each guide rail 11 and 12 is attached to a slider 16 able to slide freely along a rail portion provided on each frame base 15.
Guide member driving devices 17 are provided for moving each of both guide rails 11 and 12. As a result, both guide rails 11 and 12 are made to approach and move away from lead frame L/F by the operation of said guide member driving devices 17. Furthermore, said guide member driving devices 17 are composed of pulse motors 18a and 18b mounted on the above-mentioned frame bases 15, male screws 19 coupled to the output shafts of said pulse motors, and nuts 20 fastened to both guide rails 11 and 12 which screw onto said male screws 19.
The following provides an explanation of loader 2 and unloader 9 arranged so as to be located on both sides of the above-mentioned guide rails 11 and 12. Furthermore, since loader 2 and unloader 9 mutually have similar constitutions, a detailed explanation is provided only for the constitution of loader 2, with that for unloader 9 omitted.
As shown in FIG. 1, loader 2 has an elevator mechanism 22 for lowering or raising magazine M at intervals of the arrangement pitch of lead frames L/F in order to take out a plurality of lead frames L/F arranged and contained in said magazine M one at a time using the above-mentioned frame feeding device (not shown), and elevator mechanism base 23 equipped with said elevator mechanism 22. This elevator mechanism base 23 moves in the direction shown by arrow S, namely the direction parallel to direction of movement T of the above-mentioned both guide rails 11 and 12, and its position can be adjusted in said direction S by turning knob 25.
A pair of stocker guides 27a and 27b, formed to each have a cross-section in the shape of the letter "L", are provided on elevator mechanism base 23. One stocker guide 27a is fixed on elevator mechanism base 23, while the position of the other stocker guide 27b can be adjusted in the direction shown by arrow U, namely the lengthwise direction of magazine M.
Two each, for a total of four, regulating members 28a to 28d are attached to the insides of both of the above-mentioned stocker guides 27a and 27b. These regulating members 28a-28d engage with magazine M to regulate its movement. Two regulating members 28a and 28b are each fastened to stocker guides 27a and 27b, while the position of the other two regulating members 28c and 28d can be adjusted in the direction shown by arrow V, namely the direction of the width of magazine M.
The following provides an explanation of the operation in the case of performing adjustment of the transport apparatus so as to match the width of the lead frames L/F to be handled in the apparatus having the above-mentioned constitution.
To begin with, pulse motors 18a and 18b (see FIG. 2) are rotated and driven based on a command signal emitted from a controller (not shown) consisting of a microcomputer and so forth. The amount of rotation of said pulse motors is converted into the amount of advance or regression of nuts 20 resulting in both guide rails 11 and 12 moving to the movement limit positions in the direction in which they move away from each other.
Next, a single lead frame L/F for adjustment of the transport path is handled by an operator, and a reference hole (not shown) formed in said lead frame L/F is fit onto a projection (not shown) serving as a reference provided on heater plate 5. As a result, island 13 formed in lead frame L/F on which IC chip 1 is mounted aligns with indentation 5a (see FIG. 3) of heater plate 5.
Furthermore, as shown in FIG. 2, lead frame L/F is held by pressing from above by lead frame clamp 29, and bonding origin 30 is set in the center of IC chip 1 and island through opening 29a of said lead frame clamp 29 by operating bonding device 7 (shown in FIG. 1).
Following this procedure, pulse motors 18a and 18b are rotated in reverse so that both guide rails 11 and 12 approach lead frame L/F. Moreover, the gaps between the sides of both said guide rails and lead frame L/F are set to an optimum value.
Next, magazine M, containing a large number of the above-mentioned lead frames L/F, is loaded on loader 2 and the position of said magazine M is regulated by an operator manually performing each of the positional adjustments of stocker guide 27b and regulating members 28c and 28d. Furthermore, at this time, the position of said regulated magazine M is adjusted in the direction of width so that lead frames L/F pushed out from this magazine M smoothly enter between both guide rails 11 and 12. This positional adjustment is performed by an operator suitably turning knob 25 (see FIG. 1) to adjust the position of elevator mechanism base 23 equipped with each of the above-mentioned regulating members. In addition, aside from the above procedure, adjustment is made to provide clearance between each of regulating members 28a to 28d and magazine M so that raising and lowering operation of magazine M by elevator mechanism 22 is performed smoothly.
On the other hand, adjustment similar to that of the above-mentioned loader 2 is also performed for unloader 9.
This then completes adjustment of the transport path.
Although above-mentioned adjustment of the transport path is performed to adjust the intervals between guide rails 11 and 12 and regulating members 28a to 28d corresponding to changes in the type of lead frame L/F (magazine M) to be transported, aside from said adjustment, during replacement of heater plate 5, adjustment of the transport path following a procedure similar to that described above is also performed in the case relative displacement occurs between indentation 5a, for fitting with the island, provided on heater plate 5 and island 13. However, in this case, instead of adjusting the intervals between the guide rails and regulating members, both guide rails 11 and 12 and all regulating members 28a to 28d are shifted in position in the same direction by the amount of the above-mentioned relative displacement to align island 13 with the above-mentioned indentation 5a. Furthermore, in order to shift all regulating members 28a to 28d in the same direction, knob 25 (see FIG. 1) must be suitably turned by an operator, and the position of elevator mechanism base 23, on which each of said regulating members is equipped, must be adjusted.
As described above, in the substrate transport apparatus and substrate transport path adjustment method of the prior art, adjustment work must be performed manually by an operator to align indentation 5a of heater plate 5 with island 13 of a lead frame L/F to be transported whenever the type of said lead frame L/F changes or heater plate 5 is replaced, thus resulting in the disadvantage of creating tedious and complicated work for the operator and consuming much time.